Radiation diffractive materials based on crystalline colloidal arrays have been used for a variety of purposes. A crystalline colloidal array (CCA) is a three-dimensional ordered array of monodispersed colloidal particles. The particles are typically composed of polymer latex, such as polystyrene, or an inorganic material, such as silica.
Such colloidal dispersions of particles can form crystalline structures having lattice spacings that are comparable to the wavelength of ultraviolet, visible, or infrared radiation. These crystalline structures have been used for filtering narrow bands of selected wavelengths from a broad spectrum of incident radiation, while permitting the transmission of adjacent wavelengths of radiation. Alternatively, CCAs are fabricated to diffract radiation for use as colorants, markers, optical switches, optical limiters, and sensors.